1. Field of the Invention
The present invention relates to sutures to repair fractured bones, torn tendons, torn menisci, and the like and more particularly to sutures secured with buttons, locking tabs or other fasteners.
2. Description of the Related Art
Problems associated with failure of flexor tendon/ligament repairs (particularly in the hand) are: breakage of sutures due to their limited tensile strength, weakening of the suture by the knot, excess bulk of the knot, loss of purchase of the suture, and partial or full rupture of the tendon/ligament repair or tearing of the device or material through the collagen fibers. This can result in repeat surgery, increased pain, additional therapy, reduced flexion of the digits due to adhesions, and increased cost, all associated with this very common problem. Strength of the anastomosis is normally based on the strength observed immediately following surgery. However, from the third to twelfth day, softening of the tendon/ligament occurs, and the strength of the repairs decreases.
The repair strength of common two-strand repairs (such as the Kessler stitch shown in FIG. 12) is inadequate, even with an epitendinous horizontal mattress or running-lock suture placed at the anastomosis. In such a repair, the strength after installation is about 2,500 grams, but decreases to about 1,200 grams within one week after surgery. Since this strength can be exceeded by even mild to moderate active tendon/ligament force, it becomes obvious that a more robust tendon/ligament repair method is required. More complex four and six-strand sutures have been tried and demonstrate increased strength of repair, but the difficulty of the anastomosis is greatly increased.
In addition, major disruptions of the tendon/ligament sheath are often required during normal repair of tendon/ligament lacerations. This causes loss of vascularization, and the formation of localized tissue adhesions between the sheath and the tendon/ligament. These adhesions are a form of scar tissue, which interrupts normal motion of the tendon/ligament within the sheath, and prevents full range of motion of the associated joint. Filleting of the sheath to expose the ends of the tendon/ligament for repair disrupts the pulley, causing bowstringing, and is not acceptable technique.
These problems have been known for years, and numerous techniques for internal suturing have been tried. An alternative, external suture device was developed by the present inventors, and, although the strength carrying properties of this device were excellent, the external device was difficult to install and left a large number of suture filaments on the surface of the tendon/ligament. Even though several incremental improvements have been made in the surgical procedures, a truly successful, highly reliable method for repairing small tendons/ligaments in the hand remains to be found.
By most current methods, the ends of the injured tendon/ligament are exposed axially above and below the laceration by separating the tendon/ligament sheath and pulling the tendon/ligament out. Internal/external fixation is applied using manual suturing techniques. The most successful techniques use a mattress, zig-zag or loop-type of suture to place the tensile load further from the laceration and to purchase or gather the tendon/ligament filaments. [The filamentous collagen structure of tendon/ligament lends itself to failure of sutured repairs due to "raking" or tearing apart of the parallel longitudinal fibers]. The primary, load-carrying suture may be preceded or followed by a series of small approximating sutures, placed directly at the interface of the laceration to prevent splaying or misalignment of the tendon/ligament filaments at the site of the wound.
The installed loads (tension and compression) are difficult to control and often the installed suture pulls out of the lacerated tendon/ligament, or fails at a knot, due to either passive or active stress imposed by natural biological loads or by therapy. In addition, slippage of the surgical repair (or misalignment) can result in a gap between the tendon/ligament faces, leading to massive adhesions connected to the tendon/ligament sheath and other adjacent tissues. In addition, adhesions are worsened by opening the tendon/ligament sheath to expose the length of tendon/ligament necessary for most repairs. Using a multiple-windowing technique for flexor tendon/ligament injuries in zones 1 and 2, less damage is incurred to the vincula, tendon/ligament sheath, and pulley structures, reducing adhesions and helping to prevent "bow-stringing."
In a related concept, a primary problem with repair of small bones is their location in a patient's body. The small bones are primarily located in the hands and feet. However, the soft tissue overlying the bones in the hands have a complex anatomy. The primary method currently used to hold the fractured portion together during healing is the screw, or pin, (or combination of these) which has the drawback of having directional rigidity. This increases the problem of precisely aligning the drill holes in order to properly insert the screw or pin and increases the time for performing the procedure.
An additional problem with repairing bones is the tendency for membranes, blood vessels, nerve tissue, and the like, to become wrapped around the filament or wire while the drilling procedure is occurring. There is, thus, a need for a protective bearing surface or mechanized sheath to separate the rotating wire from the other tissues. The sheath would not rotate.
Pierce, U.S. Pat. No. 2,760,488, shows the desirability of drilling through bone with a wire and fastening a button (13) on each side of the bone. However, Pierce requires the use of a threaded button which must be screwed onto the wire.
The patent to Halloran, U.S. Pat. No. 3,489,143, shows the use of a button (23) which is used to increase the tension on a pin (P). The tension is increased by the use of threads on the pin and the button. The button is only found on one side of the fracture line (16).
The patent to Hunt, U.S. Pat. No. 4,590,928, shows a button-like structure which is similar in shape to the present invention. However, the system of operation disclosed in Hunt is substantially different. In Hunt, a hole (24) is drilled in a bone to a depth slightly deeper than the button (10). The button is then inserted in the hole. A stud (20) is then pounded into the recess (16) in the button. The stud extends only slightly further than the button in operation. The buttons are attached to a plate which extends on each side of a fracture, on the same side of the bone (FIG. 11). In an alternative arrangement (shown in FIGS. 16-17), a flexible wire is used with the button, but it is wrapped around the button to secure the wire. Thus, in operation, these buttons and the securing of the bone does not operate in the same way, nor are the structures that similar.
The most relevant patent is the patent to Reese, U.S. Pat. No 4,796,612. Reese shows a pin which is inserted through a bone. The pin has a hook (22) to secure the pin to the bone on one end and on the other end there is a button (26). The button has a ratchet-like protrusion (28) which allows for flexibility in the length of the pin.